Slopes and Intercepts

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Slopes and Intercepts Lesson 1.2
y mx b ax by c
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Objectives
Glossary Terms

• Graph a linear equation.
• Write a linear equation for a given line in the
  coordinate plane.

slope of a line slope-intercept form standard
form horizontal line vertical line x-intercept y-i
ntercept
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Slopes of lines
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SLOPE OF A LINE
The slope, or steepness of a line, is the ratio
of the change in y to the change in x or It
is often called the rise over the run.
?y ?x
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Rules and Properties
Slope of a line
Point 1 (x1, y1) Point 2 (x2, y2) slope m
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FIND THE SLOPE
of the line through points (7,2) and (1,1)
1/6
of the line containing the points (3, 5) and
(-2, -6)
11/5
of the line containing the points (-5, 3) and
(3, -4)
-7/8
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Exploring Slopes
Graph each pair of equations. Describe how the
slopes are alike and how they are different.
Y x and y x
Y x and y x
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y x and y -x
y x and y x
Make a conjecture about the slopes of y mx when
m lt 0 and when m gt 0.
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Puff! Puff! Positive Slope
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Wheee! Negative Slope
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Exploring Slopes
Find the slope of the line containing the points
(-3, 3) and (2, 3).
The slope is 0
The graph of a line with zero slope is a
horizontal line.
(2, 3)
(-3, 3)
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Find the slope of the line containing the points
(-2, 1) and (-2, 3)
The slope is 2/0 (undefined)
The graph of the line with undefined slope is a
vertical line
(-2, 3)
(-2, 1)
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YawnZzzzzzz Zero Slope
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Yikes! No Slope!
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MATCH THE SLOPE
a
1. Positive 2. negative 3. 0 slope 4. no slope
(or undefined slope)
b
c
d